Dynamic power reduction technique for ultrasound systems

ABSTRACT

A dynamic power reduction method and apparatus for use in an ultrasound system are described. In one embodiment, the ultrasound system comprises: a transducer assembly and imaging subsystem having a transmit data path having a transmitter to transmit acoustic signals and a receive data path having including signal acquisition circuitry with a receiver to receive acoustic signals representing echoes; a plurality of real-time signals indicative of status of imaging operations being performed by the transmit and receive paths; a clock generator to generate one or more clocks for use by the transmit and receive data paths; clock gating circuitry coupled to the clock generator and the transmit and receive paths and having circuits to gate clocks to at least one of the transmit and receive paths; and a clock gating controller coupled to the clock gating circuitry to control the circuits to gate or pass clock signals to at least one of the transmit and receive paths automatically in response to receipt of one or more signals from the plurality of real-time signals.

FIELD OF THE INVENTION

Embodiments of the present invention relate generally to ultrasoundsystems; more particularly, embodiments of the present invention relateto performing power management in ultrasound systems based on real-timesignals.

BACKGROUND

System power consumption in an ultrasound machine represents asignificant problem for a designer. There are a number of adverseeffects resulting from high system power consumption. Such ultrasoundmachines include larger, more expensive power supplies, have shorterbattery lives, increased internal operating temperature, utilize activecooling components that add system cost, complexity and noise, and havean increased physical footprint.

Power consumption has been addressed at a macro level. Morespecifically, from a historical perspective, the power consumptionproblem in ultrasound machines has been addressed by defining sleepstates for the machine that are generally under the control of theultrasound machine's software. In the sleep state(s), portions of thesystem are put in a low power state (e.g., a lower power consumptionstate) by slowing or stopping the digital clock(s) controlling theblock(s). The result is placing portions of the system in a lower powerstate is the reduction, and potentially minimization, of the dynamicpower of the system. These states are generally defined at a macro levelsuch that they do not occur when performing macro functions such asactive imaging, and generally are applied when the ultrasound machine isidle.

FIG. 1 illustrates power usage at a macro level during an ultrasoundexam. In the Imaging state, data is acquired and displayed in real-time.At this time, the system power consumption is generally at a maximum asmost of the electronics are active. When the user stops imaging andreviews the acquired data, the system software can shut down most of theelectronics associated with data acquisition while leaving the displayand image recall electronics running. This state of the ultrasoundmachine is often referred to as a Freeze state. During an exam, the usermay toggle between Imaging and Freeze states multiple times. Finally,after a certain time duration in the Freeze state, the system softwaremay shut down the display and enter an even lower power state depictedas Idle in FIG. 1.

To exploit the sleep state concept, the system software must be writtento recognize opportunities to go to sleep and events requiring thesystem to wake up. The net effect is that the software design andverification are complicated to achieve power savings.

SUMMARY OF THE INVENTION

A dynamic power reduction method and apparatus for use in an ultrasoundsystem are described. In one embodiment, the ultrasound systemcomprises: a transducer assembly and imaging subsystem having a transmitdata path having a transmitter to transmit acoustic signals and areceive data path having including signal acquisition circuitry with areceiver to receive acoustic signals representing echoes; a plurality ofreal-time signals indicative of status of imaging operations beingperformed by the transmit and receive paths; a clock generator togenerate one or more clocks for use by the transmit and receive datapaths; clock gating circuitry coupled to the clock generator and thetransmit and receive paths and having circuits to gate clocks to atleast one of the transmit and receive paths; and a clock gatingcontroller coupled to the clock gating circuitry to control the circuitsto gate or pass clock signals to at least one of the transmit andreceive paths automatically in response to receipt of one or moresignals from the plurality of real-time signals.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood more fully from the detaileddescription given below and from the accompanying drawings of variousembodiments of the invention, which, however, should not be taken tolimit the invention to the specific embodiments, but are for explanationand understanding only.

FIG. 1 illustrates power usage at a macro level during an ultrasoundexam.

FIG. 2 illustrates one embodiment of an ultrasound transducer probehaving an ultrasound transducer assembly.

FIG. 3 illustrates a simplified description of frame acquisition fordisplay performed by an ultrasound machine.

FIG. 4 illustrates the activity of one embodiment of an ultrasoundmachine while imaging.

FIG. 5 illustrates basic actions of the clock(s) of a receive path of anultrasound machine.

FIG. 6 is a block diagram of one embodiment of a portion of anultrasound machine.

FIG. 7 is a flow diagram of one embodiment of a process for setting updynamic power reduction for an ultrasound machine.

FIG. 8 is a flow diagram of one embodiment of a power reduction processfor use by an ultrasound machine.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to providea more thorough explanation of the present invention. It will beapparent, however, to one skilled in the art, that the present inventionmay be practiced without these specific details. In other instances,well-known structures and devices are shown in block diagram form,rather than in detail, in order to avoid obscuring the presentinvention.

An ultrasound system having dynamic power reduction and method for usingthe same are disclosed. In one embodiment, the dynamic power reductionis performed using hardware of an acoustic signal path to automaticallydetect power saving and transparently control digital clocks without theintervention of the system software. In one embodiment, thehardware-based dynamic power reduction is performed in cooperation withor in addition to the macro sleep conditions discussed above. In oneembodiment, the hardware-based dynamic power reduction is configured toreduce power while actively imaging. In one embodiment, the powerreduction is equal to or greater than the software-controlled sleeptechniques discussed above and have the added benefit of no additionalsoftware complexity.

FIG. 2 illustrates one embodiment of an ultrasound transducer probehaving an ultrasound transducer assembly configured in accordance withan embodiment of the disclosed technology. Referring to FIG. 2,ultrasound transducer probe 200 includes an enclosure 210 extendingbetween a distal end portion 212 and a proximal end portion 214.Enclosure 210 is configured to carry or house system electronics (e.g.,one or more processors, integrated circuits, ASICs, FPGAs, beamformers,batteries and/or other power sources) disposed in an interior portion orcavity of enclosure 210. The system electronics (not shown) areelectrically coupled to an ultrasound imaging system 230 via a cable 218that is attached to the proximal end of the probe.

At the probe tip, a transducer assembly 220 having one or moretransducer elements is electrically coupled to the system electronics.In operation, transducer assembly 220 transmits ultrasound energy fromthe one or more transducer elements toward a subject and receivesultrasound echoes from the subject. The ultrasound echoes are convertedinto electrical signals by transmit receive circuitry and electricallytransmitted to the system electronics and to electronics (e.g., one ormore processors, memory modules, beamformers, FPGAs, etc.) in ultrasoundimaging system 230 configured to process the electrical signals and formone or more ultrasound images.

Capturing ultrasound data from a subject using an exemplary transducerassembly (e.g., the transducer assembly 220) generally includesgenerating ultrasound, transmitting ultrasound into the subject, andreceiving ultrasound reflected by the subject. A wide range offrequencies of ultrasound may be used to capture ultrasound data, suchas, for example, low frequency ultrasound (e.g., less than 15 MHz)and/or high frequency ultrasound (e.g., greater than or equal to 15 MHz)can be used. Those of ordinary skill in the art can readily determinewhich frequency range to use based on factors such as, for example, butnot limited to, depth of imaging and/or desired resolution.

In one embodiment, ultrasound imaging system 230 includes ultrasoundcontrol subsystem 231 having one or more processors. At least oneprocessor causes electrical currents to be sent to the transducer(s) ofprobe 200 to emit sound waves and also receives the electrical pulsesfrom the probe that were created from the returning echoes. A processorprocesses the raw data associated with the received electrical pulsesand forms an image that is sent to ultrasound imaging subsystem 232,which displays the image on display screen 233. Thus, display screen 233displays ultrasound images from the ultrasound data processed by theprocessor of ultrasound control subsystem 231.

In one embodiment, the ultrasound system also has one or more user inputdevices (e.g., a keyboard, a cursor control device, etc.) that inputsdata and allows the taking of measurements from the display of theultrasound display subsystem, a disk storage device (e.g., hard, floppy,compact disks (CD), digital video discs (DVDs)) for storing the acquiredimages, and a printer that prints the image from the displayed data.These also have not been shown in FIG. 2 to avoid obscuring thetechniques disclosed herein.

FIG. 3 illustrates a simplified description of frame acquisition fordisplay performed by an ultrasound machine. A frame represents theamount of data needed to form an image on a display. The successiveacquisition and display of frames of data allows the ultrasound machineto show the motion of the object being observed.

Referring to FIG. 3, a frame consists of multiple (N) transmit beams 303generated by transducer 301 toward an object of interest 304 that islocated at a depth from skin line 302 and the echo returns from each ofthe transmit beams 303. In one embodiment, these beams 303 are closelyspaced in time to minimize the time to produce a frame. The frame rate,which indicates how often the display is updated, is generally relatedto the acquisition time of the frame. For many applications, theultrasound machine does not need to operate at a maximum frame rateeither because the display electronics cannot keep up or because theuser cannot perceive changes from one frame to the next. There is oftena gap from the end of one frame to the start of the next which isreferred to herein as the Frame Holdoff Time. FIG. 4 illustrates theactivity of one embodiment of an ultrasound machine while imaging.Referring to FIG. 4, multiple transmit/receive beams are shown forFrames 1-N that are obtained over time. Between each of these frames isthe Frame Holdoff Time.

Each of the N transmit/receive beams 303 in a frame can be furtherexamined in terms of its activity. For the sake of simplicity, thereceive path is discussed below in terms of dynamic power reduction;however, it should be understood that the dynamic power reductiontechniques disclosed herein may be applied to the transmit path as well.In one embodiment, the transmit path refers to the electronics used toexcite the individual transducer elements. Some common components of thetransmit path are: a group of high voltage driver circuits used toenergize the transducer elements, a set of delay circuits controllingthe timing of signals to the high voltage drivers to control the focusof the generated acoustic beam and a waveform table (e.g., lookup table(LUT) or other memory) controlling the shape of the signal into the highvoltage drivers. In one embodiment, the receive path comprises theelectronics used to process the low level echoes detected by thetransducer elements in response to the transmit beam. Typical operationsperformed by the electronics are: amplification of the return signalsusing both fixed and time variable amplifiers, filtering, signalconversion from the analog to the digital domain and receivebeamforming. This last operation includes time variable digital gains tocreate a receive aperture with time alignment of the digitally sampledreturn signals to form a coherent receive beam.

FIG. 5 illustrates basic actions of a receive path's clock(s) of oneembodiment of an ultrasound machine. There are a number of events usedto selectively turn the receive path clock on/off dynamically within thecontext of the timing for a single transmit/receive beam. This is adeparture from the macro control described above as the clock isdynamically starting and stopping during imaging. In one embodiment, thedecision to start and stop the clock is based on real-time signalsduring data acquisition.

Referring to FIG. 5, the receive path clock is off (501). The receivesignal path has many parameters that are unique for each receive channelduring a given transmit/receive operation. In one embodiment, theparameters are those discussed above with respect to the transmit andreceive paths. In one embodiment, the parameters include individualtransmit and receive delays for each transmitter and receiver, data tocontrol time variable gains, and/or channel calibration data. In oneembodiment, the clock to the receive path is active (502) in order toprogram the parameters (T1→T2 in FIG. 5). When programming hascompleted, the clock can be shut off (503) and remain off (T2→T3) untilvalid echo return data reaches the transducer at which point the clockremains on (504) for the duration of the data acquisition time (T3→T4).Finally, the clock shuts off (505) and remains off until it is time tore-program the receive path for the next acquisition.

FIG. 6 is a block diagram of one embodiment of a portion of anultrasound machine. Referring to FIG. 6, the ultrasound machine includesa clock gating control subsystem 601 coupled to a clock generator 602.In one embodiment, clock generator 602 includes a phased lock loop (PLL)603 to generate clock signals. Clock generator 602 provides free runningclocks 606 to subsystem 607 and ultrasound control subsystem 610. In oneembodiment, subsystem 607 is part of the imaging subsystem and includesreceive path 608 to receive and process acoustic signals (e.g., echoes)and a status and control module to provide state and control signals toclock gating control subsystem 601. In one embodiment, subsystem 607includes the transmit path for the ultrasound machine to generate andtransmit acoustic signals for the ultrasound machine.

Ultrasound control subsystem 610 controls operations of the ultrasoundmachine. In one embodiment, ultrasound control subsystem 610 generatesstatus signals. In one embodiment, ultrasound control subsystem 610generates status signals that are send to and received by clock gatingcontrol subsystem 601.

In one embodiment, the signals that are generated by subsystem 607 andultrasound control subsystem 610 that are sent to and received by clockgating control subsystem 601 are real-time signals that comprise: afirst signal indicating a user has indicated a desire to freeze theimage currently being display on a display of the ultrasound system(e.g., freeze signal 621); a second signal indicating a start of a line(e.g., Start of Line signal 622); a third signal indicating registersare being programmed (the registers being for the receive path) (e.g.,programming registers signal 623); a fourth signal indicating thereceive path has been enabled to receive echoed acoustic signals (e.g.,Receive_start signal 624); and a fifth signal indicating an end of theline has been reached (e.g., End of Line signal 625).

Clock gating control subsystem 601 uses signals 621-625 to perform clockcontrol by gating/ungating clocks to different portions of theultrasound machine. In one embodiment, clock gating control subsystem601 uses signals 621-625 to perform clock control by gating/ungatingclocks to different portions of the ultrasound machine according to thetypical transmit/receive beam timeline during acquisition as shown inFIG. 5. For example, clock gating control subsystem 601 controls gate604 to enable and disable one or more clocks 605 to receive path 608.For example, in response to freeze signal 621, clock gating controlsubsystem 601 controls gate 604 to disable one or more clocks 605 toreceive path 608 as no echoes are going to be received while a user ofthe ultrasound machine freezes the display.

As another example, in response to programming registers signal 623,clock gating control subsystem 601 controls gate 604 to enable one ormore clocks 605 to receive path 608 while registers are beingprogrammed. After programming has been completed as indicated by achange in the programming registers signal 623, clock gating controlsubsystem 601 can control gate 604 to disable one or more clocks 605 toreceive path 608 to place it in a reduced power consumption state untilafter the transmit section has finished transmitting beams and there arevalid echoes returning to the transducer to be received by receive path608.

As yet another example, in response to receive_start signal 624, clockgating control subsystem 601 controls gate 604 to enable one or moreclocks 605 to receive path 608 to enable receive path 608 to be poweredto receive valid echoes return to the transducer to be received andotherwise disable clocks 605 to receive path to place it in a reducedpower consumption state. Similarly, clock gating control subsystem 601uses receive_start signal 624 to disable one or more clocks 605 to thetransmit path to place the transmit path in a reduced power consumptionstate while receive path 608 is receiving echoes (as the transmit pathwill not be transmitting beams during that time).

After finishing the receipt of echoes and an end of line has beenreached as indicated by End of Line signal 625, clock gating controlsubsystem 601 can control gate 604 to disable one or more clocks 605 toreceive path 608 to place it in a reduced power consumption state untila new line is going to be started and/or programming of registers is tooccur.

As yet another example, in response to start of line signal 622, clockgating control subsystem 601 controls gate 604 to enable one or moreclocks to the transmit path to enable the transmit path to be powered totransmit beams from the transducer. In one embodiment, a similar clockgating approach is applied to the transmit path in an effort to reducepower (i.e., to shut down the transmit logic when not transmitting).

In one embodiment, clock gating control subsystem 601 uses signals621-625 along with one or more conditions (e.g., conditions 640) toperform clock control by gating/ungating clocks to different portions ofthe ultrasound machine. In this case, the clock control that isperformed for certain sequences differs from that of thetransmit/receive beam timeline during image acquisition shown in FIG. 5.Thus, clock gating control subsystem 601 handles other control sequenceswhen performing clock control by gating/ungating clocks to differentportions of the ultrasound machine.

In one embodiment, these sequences include one or more of the following:

1) imaging modes where register reprogramming is not needed betweensuccessive transmit/receive beams, and thus the time interval T1→T2 is0. This is the case, for example, when reshooting of a line into anobject to obtain a series of data for use in measuring changes in motionin the object on the line; if reshooting the line, the clock(s) does notneed to be turned on during the time when the registers are normallybeing programmed; thus, the clock stays off until it is time to capturethe returning echo values.

2) dummy ping generation where no data is acquired by receive path 608but a time delay between transmit/receive beams is desired. In thiscase, there is no need to program registers during a “dummy” pinggeneration because transmit and receive are not going to occur. Thus,the clock(s) that are normally turned on when programming the registerscan remain off; and

3) system initialization or a mode change where no data is acquired byreceive path but register programming is necessary.

In the case of imaging modes where register reprogramming is not neededbetween successive transmit/receive beams, clock gating controlsubsystem 601 maintains the receive path in a reduced power state fromT0 to T3 of FIG. 5. This behavior is identified by one of the inputconditions 640. The condition represents a deviation from the baselinebehavior in which the clock is enabled in response to 623.

In one embodiment, in the case of dummy ping generation, clock gatingcontrol subsystem 601 controls, using clock gating controller subsystem601, the clocks to the receive path in response to a one of conditions640 indicating whether or not the transducer is in ping generation mode.In such a case, since no data is to be acquired but a time delay betweenthe transmit/receive beams is desired, if the ultrasound machine is in aping generation mode, clock gating controller subsystem 601 maintainsthe clock signals to the receive path in a reduced power mode via clockgating when the receive_start signal 624 indicates that receive path 608is to receive echoes.

In one embodiment, in the case of system initialization or a mode changemode changes refers to imaging modes and when the type of data beingdisplayed changes. An example of this might be to switch from a grayscale image to a color image in this case the imaging stops and thesystem is re-initialized to acquire color data, clock gating controlsubsystem 601 controls, using clock gating controller subsystem 601, theclocks to the receive path in response to a one of conditions 640indicating whether the ultrasound machine is in system initialization ora mode change. In such a case, clock gating control subsystem 601enables clocks to the receive path when programming the registers butthen does not re-enable the clocks to the receive path according to thetime that echoes are to be returned to the transducer according to thetime line in FIG. 5 as no data acquisition is to take place.

FIG. 7 is a flow diagram of one embodiment of a process to set up adynamic power reduction process. The process is performed by processinglogic that comprises hardware (circuitry, dedicated logic, etc.),software (e.g., software running on a chip), firmware, or a combinationof the three.

Referring to FIG. 7, the process begins by defining subsystems that maybe placed in low power states and the time and events associated withshutting off their clocks (processing block 701) and all system clocks(processing block 702). In one embodiment, dynamically gated clocks aretreated as independent clocks derived from free running clocks at thesame frequency. More specifically, in one embodiment, for each clock,processing logic examines all blocks attached to it and identifies whichof these blocks contains logic that can be turned off at some pointduring normal operation without changing the block's function. Then theevents associated with stopping the clock are listed.

The process continues by grouping, for each subsystem, the registersinto clock domains based on their activity in the system (processingblock 703). After grouping, the process identifies registers that willremain active at all times as they interact with the system software andmay be accessed at any time (processing block 704), identifies registersthat can enter a sleep mode only when the system is not imaging. Theseregisters may control other system components with long wakeup times(processing block 705), and identifies registers that can be shut off atvarious times while actively imaging (processing block 706). In oneembodiment, these are registers are in subsystem's data path or datapath control.

Lastly, the process defines, for each subsystem, a clock control astructure based on the inputs defined in processing block 701. In oneembodiment, the control structure is clocked by a free running clock andgenerates the real-time controls for its corresponding clock gatingcircuit.

FIG. 8 is a flow diagram of one embodiment of a power reduction processfor use by an ultrasound machine. The process is performed by processinglogic that comprises hardware (circuitry, dedicated logic, etc.),software (e.g., software running on a chip), firmware, or a combinationof the three.

Referring to FIG. 8, the process begins with processing logic monitoringa plurality of real-time signals indicative of status of imagingoperations being performed by the transmit and receive paths of anultrasound transducer during use of the ultrasound transducer(processing block 801).

While monitoring the real-time signals, processing logic automaticdetects a state in which one or both of the transmit and receive pathsof an ultrasound transducer can be placed in a reduce power consumptionstate in response to receipt of one or more signals from the pluralityof real-time signals (processing block 802).

In response to detecting the state, processing logic places one or bothof the transmit and receive paths of an ultrasound transducer in areduce power consumption state using clock gating circuitry controlledby the one or more real-time signals (processing block 803).

In one embodiment, placing one or both of the transmit and receive pathsof an ultrasound transducer in a reduce power consumption statecomprises controlling, using a clock gating controller, the clock gatingcircuitry, in response to the one or more of the plurality of real-timesignals, to gate a clock to the transmit path to turn off a transmitterof the transmit path after transmitting an acoustic signal for a lineand controlling the clock gating circuitry to pass a previously gatedsecond clock signal to the receive path to turn on a receiver when validecho signals are expected to arrive at the receiver.

In one embodiment, placing one or both of the transmit and receive pathsof an ultrasound transducer in a reduce power consumption statecomprises controlling, using a clock gating controller, the clock gatingcircuitry, in response to the one or more of the real-time signals, togate clocks to the transmit and receive paths at an end of one frameuntil another frame is started.

In one embodiment, placing one or both of the transmit and receive pathsof an ultrasound transducer in a reduce power consumption statecomprises controlling, using a clock gating controller, the clock gatingcircuitry, responsive to a first condition to ignore a first signal ofthe plurality of real-time signals indicating one or more receive pathregisters are being programmed, when the imaging mode indicates thatreprogramming of the one or more receive path registers for transmit andreceive operations for successive beams is not needed. In oneembodiment, placing one or both of the transmit and receive paths of anultrasound transducer in a reduce power consumption state comprisescontrolling, using a clock gating controller, the clock gatingcircuitry, responsive to the first condition, by passing clock signalsto the receive path when programming the one or more receive pathregisters and thereafter not gate the clock signals to the receive pathafter programming the one or more receive path registers while waitingfor valid echo signals return to the transducer if the transducer is inthe imaging mode in which reprogramming of the one or more receive pathregisters for transmit and receive operations for successive beams isnot needed. In one embodiment, the imaging mode includes reshooting of aline into an object to obtain a series of data for use in measuringchanges in motion in the object on the line.

In one embodiment, placing one or both of the transmit and receive pathsof an ultrasound transducer in a reduce power consumption statecomprises controlling, using a clock gating controller, the clock gatingcircuitry, responsive to a first condition, by ignoring a first signalof the plurality of real-time signals indicating a start of the receiveoperation and maintaining gating of the clocks to the receive path aftertransmit beams have been transmitted from the transducer, the firstcondition indicating the transducer is in in ping generation mode.

In one embodiment, placing one or both of the transmit and receive pathsof an ultrasound transducer in a reduce power consumption statecomprises controlling, using a clock gating controller, the clock gatingcircuitry, responsive to a first condition, by ignoring a first signalof the plurality of real-time signals indicating a start of the receiveoperation and maintain gating of the clocks to the receive path afterregister programming, the first condition indicating the transducer isin a mode in which one or more receive path registers are program yet novalid echo signal acquisition is to occur. In one embodiment, the moderelates to system initialization or a mode change.

In one embodiment, placing one or both of the transmit and receive pathsof an ultrasound transducer in a reduce power consumption state usingclock gating circuitry controlled by the one or more real-time signalscomprises controlling the circuits to gate or pass clock signals withoutintervention of system software.

In one embodiment, the process further comprises controlling, using theclock gating controller, the circuits to pass clock signals to thereceive path when programming the one or more receive path registers andthereafter not gate the clock signals to the receive path afterprogramming the one or more receive path registers while waiting forvalid echo signals return to the transducer if the transducer is in theimaging mode in which reprogramming of the one or more receive pathregisters for transmit and receive operations for successive beams isnot needed. In one embodiment, the imaging mode includes reshooting of aline into an object to obtain a series of data for use in measuringchanges in motion in the object on the line.

In one embodiment, the plurality of real-time signals comprise: a firstsignal indicating a user has indicated a desire to freeze the imagecurrently being display on a display of the ultrasound system (e.g.,freeze signal 621); a second signal indicating a start of a line (e.g.,Start of Line signal 622); a third signal indicating registers are beingprogrammed (the registers being for the receive path) (e.g., programmingregisters signal 623); a fourth signal indicating the receive path hasbeen enabled to receive echoed acoustic signals (e.g., Receive_startsignal 624); and a fifth signal indicating an end of the line has beenreached (e.g., End of Line signal 625).

As discussed above, power reduction reduces component temperatures forincreased reliability, eases the demands on the system power supplieswhich reduces cost and increases battery life, eliminates/reduces theneed for active cooling systems which reduces cost, noise andcomplexity, simplifies software control, enables the design of smallerform factor products, and allows for the integration of additionalelectronics into sealed components such as the transducer handle.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” As used herein, the terms “connected,”“coupled,” or any variant thereof means any connection or coupling,either direct or indirect, between two or more elements; the coupling orconnection between the elements can be physical, logical, or acombination thereof. Additionally, the words “herein,” “above,” “below,”and words of similar import, when used in this application, refer tothis application as a whole and not to any particular portions of thisapplication. Where the context permits, words in the above DetailedDescription using the singular or plural number may also include theplural or singular number respectively. The word “or,” in reference to alist of two or more items, covers all of the following interpretationsof the word: any of the items in the list, all of the items in the list,and any combination of the items in the list.

Some portions of the detailed descriptions above are presented in termsof algorithms and symbolic representations of operations on data bitswithin a computer memory. These algorithmic descriptions andrepresentations are the means used by those skilled in the dataprocessing arts to most effectively convey the substance of their workto others skilled in the art. An algorithm is here, and generally,conceived to be a self-consistent sequence of steps leading to a desiredresult. The steps are those requiring physical manipulations of physicalquantities. Usually, though not necessarily, these quantities take theform of electrical or magnetic signals capable of being stored,transferred, combined, compared, and otherwise manipulated. It hasproven convenient at times, principally for reasons of common usage, torefer to these signals as bits, values, elements, symbols, characters,terms, numbers, or the like.

It should be borne in mind, however, that all of these and similar termsare to be associated with the appropriate physical quantities and aremerely convenient labels applied to these quantities. Unlessspecifically stated otherwise as apparent from the following discussion,it is appreciated that throughout the description, discussions utilizingterms such as “processing” or “computing” or “calculating” or“determining” or “displaying” or the like, refer to the action andprocesses of a computer system, or similar electronic computing device,that manipulates and transforms data represented as physical(electronic) quantities within the computer system's registers andmemories into other data similarly represented as physical quantitieswithin the computer system memories or registers or other suchinformation storage, transmission or display devices.

The present invention also relates to apparatus for performing theoperations herein. This apparatus may be specially constructed for therequired purposes, or it may comprise a general-purpose computerselectively activated or reconfigured by a computer program stored inthe computer. Such a computer program may be stored in a computerreadable storage medium, such as, but is not limited to, any type ofdisk including floppy disks, optical disks, CD-ROMs, andmagnetic-optical disks, read-only memories (ROMs), random accessmemories (RAMs), EPROMs, EEPROMs, magnetic or optical cards, or any typeof media suitable for storing electronic instructions, and each coupledto a computer system bus.

The algorithms and displays presented herein are not inherently relatedto any particular computer or other apparatus. Various general-purposesystems may be used with programs in accordance with the teachingsherein, or it may prove convenient to construct more specializedapparatus to perform the required method steps. The required structurefor a variety of these systems will appear from the description below.In addition, the present invention is not described with reference toany particular programming language. It will be appreciated that avariety of programming languages may be used to implement the teachingsof the invention as described herein.

A machine-readable medium includes any mechanism for storing ortransmitting information in a form readable by a machine (e.g., acomputer). For example, a machine-readable medium includes read onlymemory (“ROM”); random access memory (“RAM”); magnetic disk storagemedia; optical storage media; flash memory devices; etc.

Whereas many alterations and modifications of the present invention willno doubt become apparent to a person of ordinary skill in the art afterhaving read the foregoing description, it is to be understood that anyparticular embodiment shown and described by way of illustration is inno way intended to be considered limiting. Therefore, references todetails of various embodiments are not intended to limit the scope ofthe claims which in themselves recite only those features regarded asessential to the invention.

We claim:
 1. An ultrasound system comprising: a transducer assembly andimaging subsystem having a transmit data path having a transmitter totransmit acoustic signals and a receive data path having includingsignal acquisition circuitry with a receiver to receive acoustic signalsrepresenting echoes; a plurality of real-time signals indicative ofstatus of imaging operations being performed by the transmit and receivepaths; a clock generator to generate one or more clocks for use by thetransmit and receive data paths; clock gating circuitry coupled to theclock generator and the transmit and receive paths and having circuitsto gate clocks to at least one of the transmit and receive paths; and aclock gating controller coupled to the clock gating circuitry to controlthe circuits to gate or pass clock signals to at least one of thetransmit and receive paths automatically in response to receipt of oneor more signals from the plurality of real-time signals.
 2. Theultrasound system defined in claim 1 wherein the clock gating controlleris configured to control the clock gating circuitry, in response to theone or more signals, to gate a clock to the transmit path to turn off atransmitter of the transmit path after transmitting an acoustic signalfor a line and to control the clock gating circuitry to pass apreviously gated second clock signal to the receive path to turn on areceiver when valid echo signals are expected to arrive at the receiver.3. The ultrasound system defined in claim 1 wherein the clock gatingcontroller is configured to control the clock gating circuitry, inresponse to the one or more signals, to gate clocks to the transmit andreceive paths at an end of one frame until another frame is started. 4.The ultrasound system defined in claim 1 wherein the clock gatingcontroller is responsive to a first condition to ignore a first signalof the plurality of real-time signals indicating one or more receivepath registers are being programmed, when the imaging mode indicatesthat reprogramming of the one or more receive path registers fortransmit and receive operations for successive beams is not needed. 5.The ultrasound system defined in claim 4 wherein the clock gatingcontroller is configured to control the circuits to pass clock signalsto the receive path when programming the one or more receive pathregisters and thereafter not gate the clock signals to the receive pathafter programming the one or more receive path registers while waitingfor valid echo signals return to the transducer if the transducer is inthe imaging mode in which reprogramming of the one or more receive pathregisters for transmit and receive operations for successive beams isnot needed.
 6. The ultrasound system defined in claim 5 wherein theimaging mode includes reshooting of a line into an object to obtain aseries of data for use in measuring changes in motion in the object onthe line.
 7. The ultrasound system defined in claim 1 wherein the clockgating controller is responsive to a first condition to ignore a firstsignal of the plurality of real-time signals indicating a start of thereceive operation and maintain gating of the clocks to the receive pathafter transmit beams have been transmitted from the transducer, thefirst condition indicating the transducer is in in ping generation mode.8. The ultrasound system defined in claim 1 wherein the clock gatingcontroller is responsive to a first condition to ignore a first signalof the plurality of real-time signals indicating a start of the receiveoperation and maintain gating of the clocks to the receive path afterregister programming, the first condition indicating the transducer isin a mode in which one or more receive path registers are program yet novalid echo signal acquisition is to occur.
 9. The ultrasound systemdefined in claim 8 wherein the mode relates to system initialization ora mode change.
 10. The ultrasound system defined in claim 1 wherein theclock gating controller is configured to control the circuits to gate orpass clock signals without intervention of system software.
 11. Theultrasound system defined in claim 1 wherein the plurality of signalscomprise: a first signal indicating a user has indicated a desire tofreeze the image currently being display on a display of the ultrasoundsystem; a second signal indicating a start of a line; a third signalindicating registers are being programmed (the registers being for thereceive path); a fourth signal indicating the receive path has beenenabled to receive echoed acoustic signals; and a fifth signalindicating an end of the line has been reached.
 12. A method comprising:monitoring a plurality of real-time signals indicative of status ofimaging operations being performed by the transmit and receive paths ofan ultrasound transducer during use of the ultrasound transducer;automatic detecting a state in which one or both of the transmit andreceive paths of an ultrasound transducer can be placed in a reducepower consumption state in response to receipt of one or more signalsfrom the plurality of real-time signals; and placing one or both of thetransmit and receive paths of an ultrasound transducer in a reduce powerconsumption state using clock gating circuitry controlled by the one ormore real-time signals.
 13. The method defined in claim 12 whereinplacing one or both of the transmit and receive paths of an ultrasoundtransducer in a reduce power consumption state comprises controlling,using a clock gating controller, the clock gating circuitry, in responseto the one or more of the plurality of real-time signals, to gate aclock to the transmit path to turn off a transmitter of the transmitpath after transmitting an acoustic signal for a line and controllingthe clock gating circuitry to pass a previously gated second clocksignal to the receive path to turn on a receiver when valid echo signalsare expected to arrive at the receiver.
 14. The method defined in claim12 wherein placing one or both of the transmit and receive paths of anultrasound transducer in a reduce power consumption state comprisescontrolling, using a clock gating controller, the clock gatingcircuitry, in response to the one or more of the real-time signals, togate clocks to the transmit and receive paths at an end of one frameuntil another frame is started.
 15. The method defined in claim 12wherein placing one or both of the transmit and receive paths of anultrasound transducer in a reduce power consumption state comprisescontrolling, using a clock gating controller, the clock gatingcircuitry, responsive to a first condition, by ignoring a first signalof the plurality of real-time signals indicating one or more receivepath registers are being programmed, when the imaging mode indicatesthat reprogramming of the one or more receive path registers fortransmit and receive operations for successive beams is not needed. 16.The method defined in claim 15 wherein placing one or both of thetransmit and receive paths of an ultrasound transducer in a reduce powerconsumption state comprises controlling, using a clock gatingcontroller, the clock gating circuitry, responsive to the firstcondition, by passing clock signals to the receive path when programmingthe one or more receive path registers and thereafter not gate the clocksignals to the receive path after programming the one or more receivepath registers while waiting for valid echo signals return to thetransducer if the transducer is in the imaging mode in whichreprogramming of the one or more receive path registers for transmit andreceive operations for successive beams is not needed.
 17. Theultrasound system defined in claim 16 wherein the imaging mode includesreshooting of a line into an object to obtain a series of data for usein measuring changes in motion in the object on the line.
 18. Theultrasound system defined in claim 12 wherein placing one or both of thetransmit and receive paths of an ultrasound transducer in a reduce powerconsumption state comprises controlling, using a clock gatingcontroller, the clock gating circuitry, responsive to a first condition,by ignoring a first signal of the plurality of real-time signalsindicating a start of the receive operation and maintaining gating ofthe clocks to the receive path after transmit beams have beentransmitted from the transducer, the first condition indicating thetransducer is in in ping generation mode.
 19. The method defined inclaim 12 wherein placing one or both of the transmit and receive pathsof an ultrasound transducer in a reduce power consumption statecomprises controlling, using a clock gating controller, the clock gatingcircuitry, responsive to a first condition, by ignoring a first signalof the plurality of real-time signals indicating a start of the receiveoperation and maintain gating of the clocks to the receive path afterregister programming, the first condition indicating the transducer isin a mode in which one or more receive path registers are program yet novalid echo signal acquisition is to occur.
 20. The method defined inclaim 19 wherein the mode relates to system initialization or a modechange.
 21. The method defined in claim 12 wherein placing one or bothof the transmit and receive paths of an ultrasound transducer in areduce power consumption state using clock gating circuitry controlledby the one or more real-time signals comprises controlling the circuitsto gate or pass clock signals without intervention of system software.22. The method defined in claim 12 wherein the plurality of real-timesignals comprise: a first signal indicating a user has indicated adesire to freeze the image currently being display on a display of theultrasound system; a second signal indicating a start of a line; a thirdsignal indicating registers are being programmed (the registers beingfor the receive path); a fourth signal indicating the receive path hasbeen enabled to receive echoed acoustic signals; and a fifth signalindicating an end of the line has been reached.